Neddylation of Enterovirus 71 VP2 Protein Reduces Its Stability and Restricts Viral Replication.

Posttranslational modifications (PTMs) of viral proteins play critical roles in virus infection. The role of neddylation in enterovirus 71 (EV71) replication remains poorly defined. Here, we showed that the structural protein VP2 of EV71 can be modified by neural precursor cell-expressed developmentally downregulated protein 8 (NEDD8) in an E3 ligase X-linked inhibitor of apoptosis protein (XIAP)-dependent manner. Mutagenesis and biochemical analyses mapped the neddylation site at lysine 69 (K69) of VP2 and demonstrated that neddylation reduced the stability of VP2. In agreement with the essential role of VP2 in viral replication, studies with EV71 reporter viruses with wild-type VP2 (enhanced green fluorescent protein [EGFP]-EV71) and a K69R mutant VP2 (EGFP-EV71-VP2 K69R) showed that abolishment of VP2 neddylation increased EV71 replication. In support of this finding, overexpression of NEDD8 significantly inhibited the replication of wild-type EV71 and EGFP-EV71, but not EGFP-EV71-VP2 K69R, whereas pharmacologic inhibition of neddylation with the NEDD8-activating enzyme inhibitor MLN4924 promoted the replication of EV71 in biologically relevant cell types. Our results thus support the notion that EV71 replication can be negatively regulated by host cellular and pathobiological cues through neddylation of VP2 protein. IMPORTANCE Neddylation is a ubiquitin-like posttranslational modification by conjugation of neural precursor cell-expressed developmentally downregulated protein 8 (NEDD8) to specific proteins for regulation of their metabolism and biological activities. In this study, we demonstrated for the first time that EV71 VP2 protein is neddylated at K69 residue to promote viral protein degradation and consequentially suppress multiplication of the virus. Our findings advance knowledge related to the roles of VP2 in EV71 virulence and the neddylation pathway in the host restriction of EV71 infection.